Bryan and Cherry Alexander / Crevasses in the side of a tabular icebergs, with the annual layers visible. Antarctica, October 2006.

Bryan and Cherry Alexander / Crevasses in the Polar Plateau, covered by snow bridges. Antarctica, January 2006.

Bryan and Cherry Alexander / Crevasses in the Polar Plateau, partly covered in snow. Antarctica, January 2006.

Ingo Arndt / Terminal moraine of Paget Glacier, South Georgia Island

Ingo Arndt / Paget Glacier, South Georgia Island

Ingo Arndt / Nordenskjold Glacier and Allardyce Range, South Georgia Island

Bryan and Cherry Alexander / Crevasse leading deep into glacier revealing ice bridges and cold blue shadows. Cierva Cove, Antarctica, February 2009.

Jeff Wilson / Camera crew working in crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006. (Vertical dolly filming system)

Jeff Wilson / Cameraman Ted Giffords working in crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006. (Vertical dolly filming system)

Jeff Wilson / Cameraman Ted Giffords working in crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006. (Vertical dolly filming system)

Chadden Hunter / Cameraman, Ted Giffords, radios for help as an unexpected early winter storm descends on the team, the crew were working in an ice crevasse at the time, for the Mountains episode of the BBC tv series...

Jan Vermeer / Crevasses created by the melting of the ice, Antarctica